Worlds Only Leak Proof Air Spring,2500 Pounds Capacity At 50 Percent Compression,Reduces And Stabilizes Sway,Made From Proprietary And Patented Microcellular Urethane,Compress Up To 80 Pct Original Height With Full Memory Rebound,One Pc. On One Side As Replacement/Upgrade To Fact. Bump Stops,Sold as a pair left and right,Improves Overall Driver Control And Ride Comfort,Enhances Load Carrying Ability,Requires no maintenance; Proudly made in the U.S.A.,Never Load Any Vehicle Beyond The Manufacturers GVWR,Progressive Spring Rate